Carcinogenic benzene levels peak in Delhi

Petrol pumps and heavy traffic locations worst affected

Published on:

15 Mar 2012, 7:33 am

Alarmingly high levels of benzene have been reported in Delhi’s air. The levels in some areas like around IGI airport and Civil Lines, exceed the annual standard of 5 microgramme per cubic metre by 2 to 5 times. This is extremely worrying as benzene—a volatile compound of petrol—is a toxic air pollutant and a potent carcinogen. It can be extremely harmful even at trace amounts. Being volatile, it also contributes towards formation of yet another harmful gas, ozone.

The available evidences from Delhi Pollution Control Committee (DPCC) point towards benzene hotspots in heavy traffic locations in the city (see Graph 1: High benzene levels in heavy traffic locations of Delhi). Independent studies carried out by scientists at the Jawaharlal Nehru University during two different time periods—2001 and 2002 and winter months of 2007—also showed an increase in benzene levels in the city. The study also attributed the rise to increase in vehicular traffic in the city.

Graph 1: High benzene levels in heavy traffic locations of Delhi

Source: Based on data provided in DPCC’s real-time database

Graph 2: Maximum volatile organic compound levels (benzene, toluene, xylene) recorded in petrol pumps in 2009-10

Source: Meena Sehgal et al 2011, Variations in air quality at filling stations, Delhi, India, International Journal of Environmental Studies, 68:6, pages 845-849

Source: MoEF/CPCB 2011, Air quality monitoring, emission inventory and source apportionment study for Indian cities, National Summary report

The toxic risk

Improve fuel quality

Prevent evaporation

Fuel savings

How other countries are reducing evaporative losses from refueling stations?

Europe

Stage I Petrol Vapour Recovery was designed to prevent emissions of volatile organic compounds during the storage of petrol at terminals and distribution to service stations. Terminals should have floating roofs and reflective coatings so as to reduce evaporative losses from storage tanks. In addition when petrol is loaded onto tankers and transported to service stations vapour is recovered and returned to the tanker or terminal. Similar measures are deployed for underground tanks

Stage II Petrol Vapour Recovery involves over and above the state I system the provision of recovering petrol vapour displaced from the fuel tank of a motor vehicle during refuelling at a service station and transferring that petrol vapour to an underground storage tank at the service station or back to the petrol dispenser for resale

United States

Vapour Recovery Stage 2 was first developed in California and mandated in 1973. The 1990 amendments to the US Clean Air Act mandated Vapour Recovery Stage 2 in areas that had not consistently met ozone standards across the US, for service stations with throughputs greater than 0.5 million litres of petrol a year. US rules designate a vapour-recovery efficiency of 95 per cent and require California Air Resources Board (CARB)-type approval of VR2 equipment

Vapour Recovery Stage 2 is currently in place in urban areas in 27 US States, and state-wide in six States. It was introduced at a national level from November 1993 in areas that had not consistently met ozone standards

Europe